Airfoil operating mechanism



Nov. 9, 194s.

Filed Sept. 28, 1943 Af H. WESTBERG lAL AIRFOIL OPERATING MECHANISM` 3 Sheets-,Sheet l Ar'roRA/Ey.

NOV- 9,1948. A. `H. wEsTBERG ETAL AIRFOIL OPERATING MECHANISM 5 Sheets-Sheet 2 Filedsept. 28,` 1943 INVENmRS ARTHUR HAROLD WESTBERG and CHARLES S. ALDRICH l! lml 3 NOV 9, 1948- A. H. wEsTBERG ETAL.' 2,453,550

IRFO'ILA OPERATING MECHANISM Filed sept. 28,1943 s sheets-sheet 3 INVENTORS ARTHUR HAROLD wEsTBERG and BY- CHARLESS. LnRlcH y MM 6M Patented Nov. 9, `194s t UNITED STATE-s NPAira-1v1 ortica 1 `arrivasse j .AIRFoIL iornRATINo MEoHANisM Wert-nur Harold Westberg, Baldwin, and charles l iS. Aldrichfabylon, N. Y., assignorsto Repubf lic .Aviation-Corporation acorporationfof De'lai .ApplicationSeptember 28, 1943, Serial No. 504,104 v l `This invention relates to aircraft generally, and particularly to the controls for adjusting and operating the airioils `by which the aircraft is ma-` neuvered, or otherwise managed and manipulated.

The present invention proposes van additional mechanical-advantage in the operation or` ad? justament of the air -foils of 'an aircraft, which is most veffective When thenecessity for such Inechanical advantageis `the greatest, and decreases or becomes wholly ineifective as the requirements ffor it lessons or disappears. f The instant invention contemplates a control or operating means *for van -airfoil o-'f an 4aircraft having the characteristics above noted, which f will Ibe effect-ive Vat lall times ywithout yany special adjustment tor regulationon the part of `the pilot, and which is not dependent *forits operationto produce `the required "additional mechanical advantage on anything beyond the usual 'and cusi tomary manipulation "of vthe cont-rol lever, or stick, by the-operator. l

'With the above and other objects 'in view, as

will be apparent, this inventionincludes the con` struction,` combination "and `arrangeinent of parts, alias hereinafter more iullywdescribed, claimed and `illustrated in the accompanying drawings, but it is to be understood vthat the invention is limited in the embodiments itcan take, only by the scope of .the` sub-joined claims.

"In these drawings;` Fig. l is a skeletal elevation of -a system of control `levers `of an aircraiit constructed 'in accord` ance `with the present invention, for cooperation with any -`type of airfoil or control surface, illustrating vfin full Elines its neutral position and `in dottedilines its .extremepositions in fboth Adireci tions; -l i v Fig. 2 `is .an enlarged transverse Thorizontal section taken along lines 2-2 of Fig. 1;` i

Fig is an enlarged vertical section taken along Fig. 4 is a Vartica section taken along imo Fig. i7 is a transverse `section taken along v"l-Jl of Fig. .6; and

Fig. Y'Sis .an elevation of a further and modified form of structure embodying the present invention vand yalso applied to the control of ailerons.

`The vva'irioils which control the night/of `an lai-r- 7 Claims. (01.744516) craft `tend to ,become :rozex`1 or else.,` in the absence off opposingjforces, to return totheir reezowing or lin eifectiveposition` in `lnijgli speed .ight, and this tendency increases infdi- Irect `proportion jto the increase 'in .speed` "Illis condition, ,arisingyfrom tl're aerodynamic forces vacting 'upon the airf'oil, increases thel force 'necessary or required to vd isplacefthe arioil or air-` foils 4Vfrom their lfrozen position or positions. Furthermore, at high speeds, Vwhen .an airf oil has "been adjusted, it frequently` becomes necessary to apply an increased force toits control lever to maintain it in `its adjusted position. i

' 'It-is valsoawell known aerodynamic Vprinciple i that in hignspeed night, where'the tendency of` the movable :airfoil to Lfreeze `is greatest, thedegree of movement `out .of the neutral position Lof the airfoil that is required :to accomplish Va given maneuver or control of theaircraft i'slmuch less than the degree .ofniovement yrequiredat slower speeds.

Withtliese fundamentals in view, the `present i invention `proposes to provide an additional nie'- ehanieal advantage-Which is effective at its greatest efficiency ,When the Amovement of 1tlie`.=airtoil from its neutral position j is initiated, and as 'the airfoil proceeds infitsmovement from its neutral position Adecreases 'in its effectiveness. vIn short, the additional mechanical `advantage supplied'by this `invention 1is maximum when 'the airfoil reaches lits `neutral "position and `minimum when the `airfoil attains its greatest Aangleof adjust-` ment; i

Onthe other hand, `it :will` be hereinafter apparentthat the instantlinvention can. without departing from the spirit 4and scope hereof, be so adaptedthat, conversely, the `:force applied to the airfoil willi-increase as itfprogresses from its `neutral position to its position of" greatest adjustment, if such a condition is desired.`

` While the presentinvention, as applied to the control stick or lever of an aircraft, operates with equalfacilty iorthe control and operation of any movable i airfo'il of "the aircraft, either by "being embodied in the control stick of .the plane or. in

i an independent jlever, .it is Ahere rshown in Figs. A5

to 8"'for` illustrative `purposes only in icoiijunc` tion with the controlofthe ailerons. l Fig. `1 skeletally demonstrates thesa'lient 'features of this invention, regardless ofthe .type of airfoilit controls. 'In considering the form of the invention illustrated inFig. il, it must beremembered that the control .stick or lever of` an `air-` craft usually operates and ,controls two airtoils or two sets of airfoils, vz.:"t'he` elevators and the ailerons-the stick manipulating one set of airfols by its movement in one plane, and the movement of another set of airfoils by its movement in a plane at right angles thereto. In Fig. i the structure is illustrated to demonstrate the use of the present invention in the control of one type of airfoilat a.time, which-obviously-can be either of s said sets, or any other type Iof airfoil.

In the drawings, I designates the control stick or lever of an aircraft, which may of course be any type of lever for any purpose, pivoted to swing about the fixed pivot I I, said lever or stick being in effect a primary lever. When the primary lever or stick I0 is oscillated about the pivot I I, it controls one airfoil or set of airfoils, and incorporates in the control the mechanical advantage resulting from theY embodiment of the present invention in `that control.

The lower end of the control stick or primary `lever I0 below the pivot or fulcrum II, i. e. the

work armA IIB' of the lever I0, is provided with a longitudinal slot I3. This slotted end I3 ofthe work arm I0 connects this primary lever I0 by means of rollers vto be hereinafter more fully described, to a secondary leverI4, medially piv-v oted as at I to a stationary part of the fuselage (not shown). 4It is tobe noted that the pivot I I is likewise fixed to a stationary part of the fuselage. Thus, the movement oftheprimary or control lever and of the secondarylever I'4 is about their fixed pivots, I ,I-`I5, which have no relative movement. 5

The upper end of the secondary lever I4 is bifurcated vto create arms I6, which, as illustrated, particularly in Fig. 3,are positioned on opposed sidesof the extremity of the Work arm I0' of the stick or lever I0. A bolt or pivot pin I1 pierces the arms I6 of the b-ifurcated` end of the secondary lever rI4 near their extremities, and carries an intermediate roller I8 flanked by a pair of side rollers I9. By reference to Fig. 2 it will be notedthat the slot I3 in the work arm Ill' of the primary lever II) is provided along one side with central groove I3 opposed by a central outstanding ridge I 3",.on` the opposite side of-the'slot I3. The central rollerv I8 carried by the extremity of kthe secondary lever rides against v-the ridge I3", whilethe side rollers I8, positioned on each side of the central roller I8, bear against the ridges created by the groove I3 on the opposite side of the slot I3, thereby creating a rolling, independent and snug cooperative contact between therollers and both sides of the slot I3 which does not permit of any play in the Iconnection or any backlash from reaction to airfoil movement or utter. In other words, by having rollers IS-I9 operate on a common axis and/the roller I8 contact one side only of the slot and the rollers I9 contact only the other side of the slot, rolling movement is possible without play in the connection and the lever I0 permits no flutter of tl'ie controlled airfoil.

That end of the secondary lever I4 on the opposite side of the pivot or fulcrum I5 to vthe bifurcated extremity I6 thereof is connected by the usual push-pull rod ZIJ to' the airfoil under the control of the levers IIL-I4. This airfoil may be a, tab, iiap, elevator, aileron, or any movable airfoil, the principle and function of the instant invention being the same, regardless of the surface or airfoil `being controlled.

Since the connection between the work arm III of the primary lever I0 and the upper eX- tremity of the secondary lever I4 is a sliding and rolling connection, the'coextensive alignment of these levers nds the rollers I 8-I 9 at or near the upper end of the slot I3 and at the lower end of the slot I3 when these levers are moved out of alignment to one of their extreme angular positions (shown in dotted lines Fig. 1). Thus the lower end of the slot I3 may act as a stop to limit the downward movement of the rollers therein and to limit the angle of pivotal movement of the levers l--I4 out of their neutral aligned positions in either direction.

The length of the work arm I Il of the primary lever I0 is at all times determined by the distance between the fixed pivot I I and the shiftable pivot pin I'I, and as this distance varies with the angular disposition of the levers, so the length of the work arm I Il varies in direct proportion to the position of the rollers I8 and I9 in the 'slot I3. Thus, the effective length of the Work arm IIIJ is considerably shorter when the levers IIJ and I4 are in neutral or aligned positions than when they are progressing to, or are at, the Iextremes of their respective paths of movement and angularly disposed one to the other. By this arrangement the greatest mechanical advantage is applied to the secondary lever I4 by the work arm Ill of the control stick or primary lever I0 at the moment when itV is most needed, viz.: when the two levers rbegin to move, or the attempt is vmade to move them, from their neutral or aligned, coextensive positions and as the lever I'IJ and its workarm Illcontinues the movement around the pivotII, the `length of the work arm increases,y thereby reducing the additional `mechanical advantage in direct proportion to said increase in length. f

By reversing'the connection between the work arm I0 and the secondary lever I4, that is,'by placing the slotv I3 in the upper extremity of the secondary lever I4, and by positioning the rollers I8 and I9 at the extremity ofthe work arm I0 it is manifest that the results obtained by the structure are reversed and that the mechanical advantage will increase as the levers move from neutral positionstoward and to the ends of their paths of movement.` v Undercertain circumstances such a reversal` may be de sirable and useful and it may be employed without departing from the spirit and scope of the present invention. l r.

Obviously, also, within theV scope Aand spirit of the present invention Wouldrbe themodication of the system of levers4 III-I4: in which the power arm and the work arm ofthe secondary lever I4,would coincide and be situated labove the f pivot I5. In that case the rod 20 would be fattached to the secondary lever I 4 between` the fork or lever 26 is pivoted as at 21 to the cradle 24 below the plane of the floor 2| of the cockpit. Above the floor 2| the stick or lever 26 is connected to the push-pull rod 26 which reciprocates` through one of the trunnions 25 of the cradle 24 to extendto and operate the elevators. Y

The ailerons are manipulated'by the movement of the control Stick or lever 26 and the Vsimultaneousfi movement` of the `cradle kZIIfas aiunit on the trunnions 25, i. e. in a planeat right angles to'. plane of` .movement` of thestick or lever. when controlling the'` elevators... Below they iioor 42` I, the Work arm 28 Aof. theqstick.I orV primary lever 2li-28 isisecured` to, oraintegral with, the cradle 24 for movement` with itas.. it swings^ on the trunnions 25 asiabove.deseribed.-I The lower endof the. arm

28- has the eiect of bei-ng slotted or bifurcated` by `fasteningatwo `side` plates theretoy 'which constitute the`v opposed spaced tracks 29. These plates-for. tracks 29, at their free extremities, are joined and held in properly spaced` relationship by ablock 3l)` interposed therebetween and se-` cured in place-by loolts-I` piercing the block and said extremitiesiof the-plates ,29... `This block 30 constitutes the lower extremityof a slot bounded,

by the side plates or vtracks 29, the block 3|]` and the lowery extremity ofthe work arm 28 of the primary lever 26.28.

Disposed below and parallel. toA the floor 2I` of thecockpit is` a fuselage cross tie 32 spaced from` the. floor. 2l. One face of the cross tie 32 has a pivot frame-33 secured thereto, having the aligned slots 341 in the. opposed, substantially horizontal sides thereof. A. secondary lever 35 operates through` the slots 34 andtheirame 33 and is de signed to. swing about. a pivot pin 36 carried byI the frame v33. `The lower end of the secondary lever 35" is bifurcated to create the spaced arms 3'Ibetween which the extremities of the push-pull rods 38 are pivotally engagedby means of the bolt 39. These push-pull rods are conventional construction and extend in-opposite directions from the lower extremity of the secondary lever 35,1 one to. the left aileron and oneto the right aileron.

At' itsupper end thesecondary lever 35 is also bifurcated to form the spaced arms 40 designed to carry the rollers 4I mounted to rotate upon the pin 42 between the extremities of said arms.

iniiuencefoi` the control stick126f the formerrswingsiy the worloarnrz of the primary lever .Z6-281, the

cradle24 and work arm,` lever; 28being=a rigid` unit. In neutral position,theV sticl:` or control lever 2li; then-worin arm` 28 and the secondary lever@ 35'are aligned and coextensiva the rollers 4 I .caril ried by `the secondary lever 35 being `then positioned at the upperV extremity of. the sloirformedr` in the lower endet the work arm 28, i'. e. the `ex-` tremitythereo opposed totheblock im.` As` the` cradle 24 and the lever 26 move or swing in either'` direction about .the trunnions 25;` thel work: arm 280i the'primary lever, 26-2B,.which is thatrportion :thereof betweenthe pin 4210i the rollers 4/I.` andthe axis ofthe trunnions, increases in length.1 as` thefrollers `move intheslot toward the block.` 30.. Because` of this,` thegreatest mechanical` advantage occurs justas the levers 23H and 35 leave or are'` about: to leave their coextensivei aligned positions to assume positions angularlyf disposed one tothe otherandas the `degree-of the'` These rollers 4I operate in the slot at the lower end ofthe primary lever 28, defined by the side plates `29 and the' block 30 in exactly the `same manner as do the rollers I 8-I9 coact` with the slot I3 and its-sides, as illustrated in Figs. 1, 2`, 3

and"4 4'. The distance between the tracks 29 of the" primary lever 26e-28 may be accurately ad- J'usted'lby'means of shims inserted between said tracks and the block 30'in. order to minimize both friction and play in the. sliding connection between theY primary lever 2li-28 and the secondary 1ever^35i By tightening the bolts 3|, this accurate adjustment may thenV be attained.`

The angular movement of .the control stick 26-28 and the cradle 24v about the trunnions 25 is limited by adjustable stops 43H carried by the cradle 24 adjoining one of the trunnions 25 which contact fixed abutments 44 disposed on opposite sides of the trunnion. Thus, one stop 43 contacting the abutment 44-at one end of the horizontal diameter of the trunnion 25 arrests the movement of the control stick26-28 and cradlel 2t` in that direction, while the contact between the'opposed stop 4-3- and the opposed abutment 44 arrests; theL movement of the control stick and cradlein. the opposite direction. The abutments 44 are carried by one of@ the bearings 23 in which the trunnions 25 of the cradle rotate and `are. disposedjat opposed extremities of the horizontal diameter ofthat bearing; e

The operation of-this adaptation of the present invention is'identical` to that disclosed in skeletal form in Fig. 1. As the cradle 24 swings about the trunnions 25 in either direction under the l downward: movement of the beams causes the` secondary levers4f1toswing about their`respec.`

angle between them l decreases, so does" the,` mechanical advantagedecrea-se in force;

In Fig. Sua-modification of the present struce,

ture is shown Iwhichvemploys a parallel motion.

In this-form, theV controlstick 26 is mounted for?" independent pivotal movementv about pivot1-211=in thecradle 24 as in Figs. 5, 6 and 'Land thetlatten is-mounted'for pivotal movement in a planeper-i pendicular tothe plane of said independent 1novel mentrabout trunnions. 2.5and carries an4 extensionl 28 which projectsv below the licor` (not shown) of the cockpit andwhichfis fastened tothefcradle by means oibolts 281". This extensioncomprises;` two spacedv plates 29 with `a block,` 30. heldbe- I. 'Il-he .innez' beams, a bolt dlpierces them and constitutesam axle for the rollers 4 I `operating between the `plates 29'. The unitary movement of the stick 26 and cradle 24, as illustrated in dotted lines in Fig. 8, will cause the rollers 4I to move downwardly betweentheplates 29' towardtheblock 30', the beams 45 remainingalways parallel to each other. andV to their initial positions during` this movement.v Parallel to thebeams 45 below the iioor` of the cockpit is the crosstie 32 `to which` are..

pivotedI the intermediatefsecondarylevers 41, as' at 5I; The lower extremities149 ofsaid levers 41, projectzbelow` the` cross tie 32. and are pivotally connected; asat" 50ste the aileron pushfpull rods 38, thelower extremityof one leveri4'I. being connected to the piislrrpull` rod 323.1oftl1e` leftaileron, I whilethe lowerextremity` of the opposite leverv `the push-pulls rod 330i.` the 41 is connected `to rightaileron.

The unitary movement of the stick 2li-"23':andh

the cradle2'4. about the trunnions 25 in either direction from neutralposition forces the rollers 4 I. downwardly in the space between the plates 23 inthe direction of block 30, at the same time maintaining-the position of the beams 45` always: paralleltothemselves; This combined lateral and tive pivots 5I simultaneously and in the same direction pulling one rod 38 and pushing the opposed rod 38. A reversal of this movement causes the elements to move in the opposite direction in exactly the same manner. Thus the swinging movement of the control stick 26 either side from neutral causes a simultaneous bodily movement of the beams 45 laterally and in a vertical plane and the simultaneous swinging of the levers 41 about their pivots in either direction. The secondary levers 41 and the beams 45 together form a parallel motion system carried by the two pivots 5 l.

In this yform of the invention the control lever 26 and the plates 29', deiining the slot in which the rollers 4l operate, constitute the primary lever 26--28 while levers 41 constitute the secondary levers. Here two secondary levers 41 are substituted for the one secondary lever 55 shown in Figs. 5, 6 and 7, and the single secondary lever I4, shown in Figs. 1 to 4, inclusive, and at no time are the levers 41, or either of them, coextensive oraligned with the primary lever 26-28. When the device is in its neutral position, the levers `41 and the lever 26 are parallel one to the other, and normal to the floor 2l of the cockpit and the cross tie 32. When they swing in either direction, the levers 41 assume positions angularly disposed to the control stick 26, exactly as does the single secondary levers i4 in Fig. 2 and the secondary lever 35 in Figs. 5 and 6. With this exception, the structures are substantially identical `in arrangement, and regardless of this exception,

they are identical in function and results.

The inventive concepts and several illustrative embodiments thereof having been thus disclosed in the manner required by the statutes, what is claimed as new, is:

1. In an airfoil control, the combination with a primary lever, the outer extremity of the work arm of said primary lever having a slot therein, a'central longitudinal ridge on oneside of said slot, a pair of spaced ridges each at one edge of the other side of said slot, a secondary lever, a plurality of rollers carried by one extremity of the secondary lever and `adapted to operate in said slot, a number of said rollers being arranged to contact against the spaced ridges on one side of the slot and the remaining rollers contacting against the central ridge on the opposite side of the slot, and an airioil connection associated with the opposite end of said secondary lever.

2. In an airioil control, the combination with a primary lever having a slot in the outer extremity of its work arm, a pair of parallel, spaced ridges on one side of said slot, a central ridge on the opposite side of said slot, a secondary lever, a plurality of rollers operating on a common axis carried at one extremity of said secondary lever, two of said rollers being organized to operate upon the spaced parallel ridges upon one side of the slot and out of contact with the opposed side and the remaining rollers beingadapted to operate on the single central ridge of the opposite side of the slot and out of contact with the first side of the slot, and an airfoil connection associated with the opposite end of said secondary lever.

3. The combination with an aircraftv control lever having a cradle cooperating with said lever, of an extension of said lever secured to said cradle, said extension having a pair of spaced tracks at one terminal thereof, a secondary lever, a` connection between said extension lever and said secondary lever having a sliding connection between the tracks aforesaid, and an airfoil consecondary lever for operation in said slot, said nection associated with the opposite end of said' secondary lever.

4. The combination with the control lever of an aircraft, of a cradle cooperating therewith, an extension of said lever xed to said cradle, a vpair of spaced tracks at the outer extremity of vsaid extension, a secondary lever, a connection between one terminal of said secondary lever and said extension lever embodying a plurality of rollers operating upon a common axis between Ysaid tracks, a number of said rollersbeing organized to operate against one of said tracks 'and the remainder thereof to operate against the other of'` said tracks, and an airioil connection associatedwith the opposite end of said lever.

5. Ihe combination with an aircraft including a movable control surface, of a vertically disposed. control lever, a xed pivotal mounting for saidf lever situated medially of its length anddividing said lever into an upper power arm and allower work arm, a vertical secondary lever positioned below said control lever to align vertically with the latter in neutral, a xed pivotal mounting for said secondary lever situated medially of itsI length and parallel to the pivotal mounting of' the control lever and dividing said secondary lever into an upper power arm and a lower work arm, an operating connection between the work arm of the secondary lever and the movable cone. trol surface, and a Variable connection between the work arm oi the control lever and the power arm of the secondary lever.

6. In an airfoil control, the combination with,A

a primary lever having a slot in the outer ex-y tremity of its work arm, a secondary lever,A a plurality of rollers carried by one extremity of the rollers being so organized that a part thereo contact one side of the slot and the remainder contact the opposite side of saidv slot, and an airfoil connection associated with that end ofy said secondary lever opposed to the rollers.

7. The combination with a conventional aircraft control cradle and a control lever pivoted thereto, of an extension of said lever secured to said cradle at one side of the longitudinal axis oi the control lever, said extension having a longi'- tudinal slot therein, a secondary lever, a connection between said extension and oner end of saidsecondary lever slideably operating in the slot aforesaid, and an airfoil connection associated with the opposite end of said secondary lever.

ARTHUR HAROLD WESTBERG. CHARLES s, ALDRICH. i

REFERENCES CITED The following references are of record inthe file of this-patent:

UNITED STATES PATENTS 

